RALEIGH — North Carolina regulators are investigating whether Duke Energy broke the law when workers pumped contaminated water from a coal ash dump near the Cape Fear River, a state official said Monday.

State Department of Environment and Natural Resources spokesman Jamie Kritzer said the agency is determining whether Duke violated its wastewater permit at its Cape Fear Plant in Moncure.

The environmental group Waterkeeper Alliance took aerial photos of two large mobile pumps at the facility on March 10. The pumps appear to be sucking water directly from a large coal ash dump into nearby woods and a storm drain leading to a nearby waterway. Coal ash contains arsenic, lead, mercury and other toxic metals.

Duke has described the pumping as “routine maintenance” at the old coal-fired power plant, which shut down in 2012.

The new probe comes as a federal grand jury is convening in Raleigh on Tuesday as part of a criminal investigation triggered by the massive Feb. 2 spill from a Duke coal ash dump in Eden that coated 70 miles of the Dan River in toxic gray sludge.

The state has already issued notice of seven environmental violations against Duke following the disaster, the third largest spill of its kind in the nation’s history. Two of those violations were related to the spill. Five were for unlawful discharges of storm water at other Duke plants across the state. The company could face hundreds of thousands of dollars in fines.